The invention is directed to a chopper arrangement having several knives, that are fastened to a rotating vertical body, so that the uppermost blades located at the inlet have a slower circumferential speed than the lowermost blades.
DE 43 21 905 A discloses an attachment chopper for a combine. The chopper comprises a straw chopper having a horizontal axis of rotation which conducts the chopped crop material by transfer funnels to ejector blowers. The ejector blowers have vertical axes of rotation and eject the chopped crop material onto a field.
DE 44 31 802 A discloses an attachment chopper with which the straw is conducted by a horizontal screw conveyor to a vertically arranged chopper which chops the straw and simultaneously conveys it. The chopped straw leaves the rotor housing through ejection ducts attached thereto, that can be pivoted about a vertical axis.
DE 197 53 486 A discloses a chopper arrangement that is also provided with a cylindrical chopper rotor for the chopping and ejection of the crop, which rotates about a vertical axis of rotation. The crop is supplied to the chopper rotor tangentially.
One advantage for the use of chopper rotors with vertical axes of rotation lies in the fact that the kinetic energy transmitted by the chopper rotor to the chopped crop can be used for the ejection and sideways distribution of the chopped crop on the field. However, an axial supply of the chopped crop is problematical in the relatively narrow gap between the rotor and the housing. In the chopper arrangement of DE 197 53 486 A an axial supply is used, whereas with attached choppers of DE 44 31 802 A a screw conveyor is required.
It is an object of the present invention to provide a chopper arrangement with high ejection trajectory of the chopped crop having improved supply characteristics.
It is proposed that the knives be fastened to a central body that can be brought into rotation by a drive. The knives are positioned on the body in such a way that the radially outer ends of the knives are spaced at different radial distances from the axis of rotation of the body as a function of their axial position on the body. The radially outer ends of the knives are thereby arranged in the form of a cone over at least one partial region of the length of the body. The radially outer end of a knife arranged, for example, at a first end of the body is thereby relatively close to the axis of rotation. The knives following in the axial direction are located at a greater distance from the axis of rotation. In this way the circumferential velocity of the knives increases, the farther the particular knife is located away from the first end of the body. The crop material to be chopped is supplied to the first end of the body axially, tangentially or radially. The crop material is taken up relatively slowly and during its movement over the length of the chopper arrangement is accelerated by the knives. The knives may be suspended on the body rigidly or pendulously and may interact with shear bars attached to the housing.
The arrangement of the knives according to the invention results in improved supply characteristics of the chopper arrangement, since the chopped crop does not experience any great changes in velocity during its introduction into the chopper arrangement. If the chopper arrangement is applied to a combine with an axial supply, a discharge beater can be omitted between the straw shakers or the separating rotors and the chopper arrangement. However, it is also conceivable that a conveying element of this type may be configured, for example, as belt conveyor, conveyor roll, pair of conveyor rolls or a screw conveyor that guides the chopped crop together from the sides.
If the radially outer ends of the knives are arranged in the form of a cone, the ends of the knives are at a greater distance from the axis of rotation the further each of the knives is spaced axially from the first end of the body. The result is a continuous acceleration of the chopped crop on its path along the axial length of the body.
A conical arrangement of the ends of the knives or one varying in another way, can basically be attained in three ways. In one way, knives of varying length are fastened to a cylindrical body. The length of the knives is varied as they are distributed in the axial direction along the length of the cylindrical body, increasing successively. In another way, the knives are fastened to retainers of varying length that extend from the cylindrical body. The length of the retainers is varied as they are distributed in the axial direction along the length of the cylindrical body, increasing successively. The knife retainers may be configured in a blade shape in order to generate a flow of air through the chopper. Alternatively, uniformly sized knives can be fastened to a conical body. Uniform knives and are preferred as it reduces the number of different parts and for reasons of cost. In the case of a conical body, a further advantage is seen in the fact that less chopped crop can accumulate between the outer ends of the knives and the body, since the knives can be dimensioned to be shorter.
The axis of rotation of the body is predominantly vertical and may be inclined relative to the horizontal. The result of this is that the crop is ejected horizontally and is distributed homogeneously in a sideways direction on a field, without the need for (an energy-wasting) deflection of the flow of the chopped crop.
The large components of the crop to be chopped is preferably supplied at the end of the cone having the smaller dimension. It can be supplied axially, radially or tangentially. In particular, the material can be introduced into the gap between the circular envelope described by the rotating body and the housing, where a considerable portion of the length of the body equipped with knives (or the entire length) can accept the crop coming from the sideways direction.
In particular, in the case of an axial supply of the material to be chopped, cutting elements arranged at the inlet end of the body can improve their acceptance of the material, in that they mill down the incoming mat of the crop.
In a preferred embodiment, the housing of the chopper arrangement is equipped with one or more tube-shaped ejection ducts, through which the chopped crop is ejected. As a rule, the ejection duct or ducts are adjacent to the end of the cone that has the greater radial dimension. Alternatively, the height of the ejection duct may extend over the entire height of the body with the knives attached thereto. The body and the attached knives can generate a tangential airflow directed at the ejection duct that improves the ejection of the chopped material.
The ejection duct can be pivoted about a vertical axis in order to eject the chopped material in successively different directions. The pivoting movement can be continuous, in order to distribute the chopped crop over the width of the swath taken up by the combine harvesting assembly. It is also conceivable to pivot the direction or directions of ejection on the basis of the wind direction, the inclination of the terrain, or stop at a fixed position on the basis of measured conditions or conditions provided as input by an operator.
In the case that the capacity of a chopper arrangement with one body and the attached knives should not be sufficient, an obvious solution would be to arrange two bodies sideways alongside each other. Their axes of rotation can extend parallel or inclined to each other. Here it is conceivable that the bodies be installed in a common housing, or to use two separate housings.
It is appropriate if the knives are arranged on the body in a helical pattern, that is azimuthal in the direction of rotation and axially offset helically to each other, so that they improve the conveying of the chopped crop in the axial direction.
In a preferred embodiment, a blower is located adjacent to the end of the cone with larger radial dimensions. The latter is equipped with blades that rotate about the same axis as the knives. The blower accelerates the chopped crop and improves the ejection. It is conceivable, that instead of a separate blower, or in addition to it, ejector blades be attached to the larger end of the cone. Their length and/or position can be variable which can be attained by appropriate repositioning arrangements controlled manually, remotely or automatically by a control arrangement. In this embodiment the chopped crop can also be ejected through pivoted or stationary ejection ducts, that are adjacent to the blower or the ejector blades.
The blades can be driven by a gearbox inserted between the body and the blower, so that the body and the blower can rotate at different rotational speeds. Furthermore, the blades of the blower can be equipped at their outer ends with knives, that preferably interact with shear bars attached to the housing. This results in an improvement in the chopping effect.
In addition, the blower can generate an air flow in the axial direction so that chopped crop is already drawn into the inlet of the housing of the chopper arrangement and is conveyed in axial direction through the chopper arrangement. The shape of the knives fastened to the body can also be selected in such a way that they generate an axial airflow.
Furthermore, it is proposed that an intake helix be arranged on the inlet end of the body that improves the intake characteristics of the chopped crop. Intake helixes of this kind are known in themselves, for example, from axial separator rotors.
The housing of the chopper arrangement preferably conforms at least partially to the shape of the cone, so that the chopped crop passes through a gap of approximately constant dimension between the housing and the knives and is chopped there. On the interior side of the housing guide vanes may be attached that guide chopped crop and air in axial or helical direction.